I'm running openldap 2.3.43 on a Fedora 9 Linux x64-bit system. I've had
to hard reboot this system a few times without cleanly shutting it down.
upon startup, most of the time slapd hangs when trying to start due to
not shutting down cleanly. The only way to get it going again is to go
into single user mode, delete everything in /var/lib/ldap and then
loading a nightly backup.ldif with slapadd. Is are there any
settings/configuration changes I can make to slapd to have it start up
from unclean shutdowns?

Stop hard booting your system. You can try removing the alock file in
/var/lib/ldap and running db_recover manually prior to starting slapd
again, but there's no guarantee the DB you end up with is what you want.